The purpose of this application is to obtain support required to complete preparations for and to conduct the Fourth National Eye Institute (NEI) Symposium on the Epidemiology of Eye Diseases and Vision Disorders. The Third NEI Symposium on this topic was held in 1991; a great deal of progress has been made since that time with respect to understanding the prevalence, incidence, and risk factors for major eye diseases and vision disorders that affect the population of the United States. In addition, new epidemiologic and statistical methods have been developed since that time. Furthermore, the composition of the U.S. population had undergone dramatic changes, including changes in the age distribution of the population and changes caused by immigration and other factors. The goals of the Fourth Symposium are to review progress in documenting the epidemiology of eye disease and vision disorders prevalent in the U.S. population; to identify areas in which epidemiologic data are unavailable or outdated; to address emerging areas of research; to provide a forum for epidemiologists, biostatisticians, clinicians, and other vision scientists to interact and to explore opportunities for collaboration; and to stimulate interest among new investigators and trainees in ocular epidemiology. A Planning Committee has developed preliminary plans for the Fourth Symposium which will include both invited and contributed papers. A Program Committee will be appointed to assist with final organization of the program and selection of contributed papers to be presented. Only new unpublished data and findings will be accepted for presentation. Special efforts are planned to attract young investigators and investigators who are members of underrepresented minorities to participate in the Fourth Symposium as speakers and as registrants. A member of the NEI program staff will participate in future planning and in the Program Committee. Invited papers and selected contributed papers presented at the Fourth Symposium will be published in a special issue of the journal "Ophthalmic Epidemiology", by arrangement with the editor and publisher. Guest editors from the Planning Committee will be responsible for peer review and other scientific editorial tasks for manuscripts submitted for publication in the special issue of the journal.